William McGinley, a lawyer for Bachmann, acknowledged the OCE investigation in March, saying it was tied to her presidential bid and that she was cooperating with the investigation. Bachmann has denied any wrongdoing but announced in May she would not seek reelection.
In a statement Friday, McGinley said the committee's extension was routine and expressed confidence that Bachmann will be vindicated.
"Today's statement by the House ethics committee emphasizes that its customary 45-day extension does not 'indicate that any violation has occurred, or reflect any judgment on behalf of the committee,' " McGinley said. "It does not speak to the merits of this matter, and any inference to the contrary is false."
He added: "We are confident the committee will discover, upon proper review, that the highly politicized allegations made at the OCE level were baseless and without merit."
The OCE is an independent House panel run by a board of directors who are outside Congress, although some of them are former lawmakers. The OCE's investigative reports and recommendations for further investigation go to the member-run House ethics committee, the panel that decides whether rules were violated. The committee can then vote to continue investigations, launch its own formal investigations, or dismiss cases outright.
OCE referred each of the investigations to the ethics committee in June, recommending full investigations.